640931089 has 4 divisors (see below), whose sum is σ = 647538724. Its totient is φ = 634323456.

The previous prime is 640931003. The next prime is 640931111. The reversal of 640931089 is 980139046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 87740689 + 553190400 = 9367^2 + 23520^2 .

It is a cyclic number.

It is not a de Polignac number, because 640931089 - 2¹⁹ = 640406801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640931189) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3303672 + ... + 3303865.

It is an arithmetic number, because the mean of its divisors is an integer number (161884681).

Almost surely, 2^640931089 is an apocalyptic number.

It is an amenable number.

640931089 is a deficient number, since it is larger than the sum of its proper divisors (6607635).

640931089 is an equidigital number, since it uses as much as digits as its factorization.

640931089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6607634.

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 640931089 is about 25316.6168553383. The cubic root of 640931089 is about 862.1915840225.

The spelling of 640931089 in words is "six hundred forty million, nine hundred thirty-one thousand, eighty-nine".